At 4-0 down, O'Sullivan's highest break was only 27 and his pot success rate had fallen to a lowly 76%.

But the 42-year-old recovered to claim seven of the eight frames in the second session, winning his 1,000th frame at the Crucible in the process.

"You want to battle through and make the score respectable," said O'Sullivan. "When I got home last night after winning three frames, I felt I had a good result. It gave me belief today but I was not thinking catastrophic thoughts."

O'Sullivan on fitness campaign

O'Sullivan tucks into a salad in the middle of a news conference

On Friday, the top 16 players - apart from the ill Ali Carter - went through their media duties at the Crucible. O'Sullivan sat through the news conference eating a salad.

After his victory over Maguire on Sunday, O'Sullivan spoke at length about how a strict diet has improved his eating habits, leading to him "feeling so good".

He also criticised the UK's issues with weight, saying the population is "massively obese".

O'Sullivan said: "I have changed the way I eat and have a massive amount of energy. Compared to the average Briton, I will always look fit because we are not the most healthy society.

"You go to China, or to the Mediterranean, they eat proper food. It is all pre-packed meals here. You look at the state of some of our humans in the country, they are massively obese. A bit like America.

"The biggest thing for me this year is how I have eaten and am amazed how good I feel and how healthy I am.

"I want to help so many people who have problems with their weight and want to feel good about themselves. I have been in that situation and there is an answer, you have to seek the right people.

"Ever since I was a kid, I have always been on the chubby side, there is a lot of fried food at snooker clubs. Then I got into running.

'He got out of jail' - Maguire

Maguire said his defeat was a fair result and that he had expected O'Sullivan to improve on Sunday.

"Ronnie got out of jail and so he is going to be more dangerous than he already is. Yesterday I could have won the match but then he went nuts for a couple of frames and got back in the match," said the Scot.

"I will now float around the top 32 for the next few years without breaking into the top 16. I have to get on with it and accept that these boys are a step better than me. Players have improved and I have stayed the same. When they play well they are awesome, I do not have that.

"I have not won a tournament for years and all the other boys are consistent."